Note 2 - Revenue Recognition 1 (Details Textual) Pure in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Sep. 30, 2023	Dec. 31, 2022 USD ($)
Contract with Customer, Liability, Current	$ 721	$ 1,279		$ 372
Contract with Customer, Liability, Revenue Recognized	$ 1,276	368
Contract with Customer, Contracts in Progress, Number of Contracts Identified as Loss Contracts	0		0
Revenue, Remaining Performance Obligation, Amount	$ 6,175
Air Pollution Control [Member]
Contract with Customer, Asset, after Allowance for Credit Loss	$ 2,075	$ 2,285		$ 3,082